Foam flotation protein separatior

ABSTRACT

In order to reduce the noise made by a foam flotation separator working on the dispersion apparatus principle and maximise the air supply, the foam flotation separator is designed so as to comprise a dispersion pump (2) which draws in water and a gas such as air and/or ozone, a reaction chamber connected on the delivery side, a collector (5) on the upper end of the reaction chamber (4) and an expanded section (15) at the lower, outlet end of the reaction chamber (4).

TECHNICAL FIELD

The invention relates to a foam flotation separator, in particular afoam flotation protein separator for sea water aquaria, and to animpeller for a dispersion pump for dispersing gas such as air and/orozone in water for foam flotation separators of the above-mentionedtype.

A preferred field of application of such foam flotation separators is insea water aquaria, which have to be constantly filtered in order tomaintain satisfactory water quality. Of the different types offiltration foam flotation protein removal has proved particularlyworthwhile and has been adopted in various forms.

In this process the water is brought into contact with very fine bubblesof air on which organic pollutants are taken up. The air bubbles collectas a stable foam on the surface of the apparatus, from which they can beremoved.

In foam flotation protein removal a particular problem arises in theintroduction of the gas, as a rule air, which may be enriched withozone, into the water. For this purpose various methods are known:

introduction through wooden or ceramic distributors

introduction through venturi nozzles with gas intake on the deliveryside of the pump

introduction through dispersers, that is to say, pumps which draw in thegas on the intake side of the pump and mix the air bubbles with thewater at an impeller wheel in the pump housing and so comminute them.

PRIOR ART

All known devices and processes have some considerable disadvantages.Thus distributor blocks are very maintenance intensive and need to befrequently replaced. Installations with venturi nozzles need highpressure at the injector and are therefore wasteful of energy,particularly for small installations, since they need relatively largeand powerful pumps with a correspondingly greater power consumption.While the installations operating on the disperser principle givesatisfactory results even in the case of small installations, hithertoknown devices nevertheless generate a considerable amount of noise andcause considerable difficulty in adjusting the equilibrium between theamounts of gas or air and water delivered. In the case of many foamflotation separators found in aquaria air bubbles get into the aquariumtogether with the purified water, which can have harmful effects on theoccupants of the aquarium, particularly when ozone is used in the foamseparator.

From German Utility Model 92 09 563 a protein-trapping device operatingon the disperser principle is known which draws in the air with normalimpeller wheel pumps. Here the air output can in some cases and inparticular circumstances be satisfactory, but in operation these devicesgenerate a considerable volume of noise, and buzzing sounds occur. Inaddition the known devices operating on this principle cannot be adaptedto different pumps or outputs.

United States specification 3 669 883 discloses a foam flotation proteinseparator having in the relevant region a cylindrically shaped reactionchamber which is closed at the bottom. This known device is operated onthe centrifugal principle, wherein an outer, bubble-free zone is createdwhile the inner liquid column is resolved into the desired separatedproducts. As a result this apparatus, too, suffers from the noiseproblem mentioned, quite apart from the fact that the separating actionleaves something to be desired owing to the occurrence of vortexformation.

THE INVENTION

It is therefore the object of the present invention to improve thedispersion principle so that it can be used in a low-noise manner and sothat the escape of air bubbles into the aquarium is reduced or thesupply of air is optimised.

This object is achieved by the features of the main claim.

A particular feature of the invention consists in the cross sectionalenlargement of the preferably tubular reaction chamber, for in thisregion the rate of flow of the gas-water mixture introduced into thereaction tube is reduced because of the enlargement of thecross-section, so that the air bubbles come to a standstill and evenascend, and do not leave the reaction tube with the stream of water butpass into the collector with the particles which are to be removedadhering to them.

In another embodiment of the invention a prefilter is fitted on theintake side of the centrifugal disperser pump which acts as a mechanicalfilter and holds back the coarse dirt.

Preferably the enlargement of the cross-section is in the shape of afunnel at the lower end of the vertically disposed reaction tube, at theoutlet of which, in the region of the enlargement, there is preferably afilter, which can consist of a filter basket surrounding a filtersponge.

The gas-water mixture which is produced by the dispersion pump throughthe gas, i.e. preferably air, being drawn in by the reduced pressure atthe intake side and mixed with the water in the pump and broken up intoextremely fine bubbles, then passes under pressure into the upper regionof the reaction tube with a downwardly directed flow, so that the air isat first carried along with it. In the funnel-shaped enlargement of thecross-section the rate of flow is reduced, so that the air bubbles cometo a standstill and rise. The smallest air bubbles, which are stillcarried along downwards, pass with the water through a central inletopening provided in the filter basket on the inlet side into the filtersponge, which when ozone is used may also be coated or interspersed withactive carbon in order to reduce any residual ozone. The central inletopening is preferably surrounded by several smaller diameter riser holesthrough which the air bubbles which have been carried along can ascendagain in this particularly quiet zone. This arrangement prevents largeair bubbles, which would interfere with the formation of foam in theupper region of the reaction tube, from rising out of the sponge.

In order to produce a much reduced pressure at the pump and to pump alarge quantity of air simultaneously with a large quantity of water, ina further embodiment of the invention the impeller of the dispersionpump is formed as a needle wheel, as a result of which the noise ofoperation is also minimised and the air bubbles are effectively brokenup. This large quantity of air is needed in order to ensure the highcapacity of the foam flotation separator. The needle wheel preferablyconsists of a plurality of needles or pins projecting radially outwardlyin the form of a star and can be made up of several (two to ten) needledisks, each carrying needles lying in a plane, which can be pushednon-rotatably on to an axle, offset so that the needles are not inalignment in the axial direction. The axle can be in the form of anadapter, so that the needle wheel of the invention can be adapted todifferent types of pump. The modular construction of the needle wheelmakes it possible to use the needle disks in pumps of different powerand having pump housings of different dimensions.

A further optimisation of the efficiency of the foam flotation separatorof the invention is obtained through the form of the collector which isfitted on to the reaction tube as an open bottomed releasable foam headand may be provided with a lid having air escape holes.

The rising air bubbles are dewatered in the upper region of the foamflotation separator and the foam is forced into the foam head, where itis stored. Since the foam head is fitted releasably on the reactiontube, it can easily be removed for regular cleaning. Its special formconsists in its double-walled construction, with the walls being joinedintegrally together at their lower rims and the inner wall being shorterthan the outer one in the axial direction.

While the outer of the two coaxial walls of the foam head iscylindrical, the inner wall forming the foam tube tapers in a funnel orconical shape from the lower rim towards the interior of the foam head,without any edges, to less than half its original diameter, whichpreferably corresponds to that of the upper rim of the reaction tube.This conical or funnel-shaped contour leads in the course of thedewatering, which involves a reduction in volume, to a constant rate ofascent of the bubbles and to a particularly easy expulsion of the foaminto the outer, annular region of the foam head.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be explained in more detail, by way of example,with reference to an embodiment shown in the accompanying drawings, inwhich:

FIG. 1 shows a diagrammatic perspective view of a foam flotation proteinseparator; and

FIG. 2 is an axial front view of an impeller for the dispersion pump ofthe foam flotation separator shown in FIG. 1.

MODES OF CARRYING OUT THE INVENTION

The foam flotation separator 1, which is intended to be immersedcompletely in the water of the aquarium to be treated, comprises, in theembodiment shown, the following components:

a dispersion pump 2,

a prefilter fitted before the pump 2 on the water intake side,

a reaction tube 4 fitted after the pump 2 on the delivery side, and

a foam head 5 fitted on to the top of the vertical reaction tube 4.

For the reasons already explained, the dispersion pump 2 is provided inthe present exemplary embodiment with an impeller 6 having the formshown in FIG. 2 instead of the usual impeller wheel of the centrifugalpump. This impeller is in the form of a needle wheel and suitablyconsists of a plurality of needle disks 6a, 6b pushed in succession onto an axle 7. According to the desired capacity and the dimensions ofthe pump housing, from two to ten of the flat needle disks 6a, b,, canbe fitted on a corresponding axle 7 in the form of an adapter dependingon the type of pump, in such a way as to produce the offset of theneedles shown in FIG. 2, which leads to an increased efficiency ofdispersion. The needles 8 are preferably circular in cross-section, andin each case eight to twelve of them are arranged on a diskperpendicular to the axle 7 to form a star.

The mechanical prefilter 3 consists of a perforated housing or mesh cage9 which encloses a sponge 11. Water drawn in enters the prefilter 3 onall sides as shown by the arrows A, is freed from coarse dirt and passesas shown by the arrow B through a connecting neck 12 into the dispersionpump 2, which by means of the impeller 6 simultaneously draws in air oranother treatment gas, which may be enriched with ozone, through an airintake branch 13 as shown by the arrow C, so that turbulence of the gaswith the water and intensive breaking down of the gas bubbles intosmaller bubbles down to microbubbles takes place (dispersion).

This "dispersion" mixture is pumped by the pump 2 via the delivery pipe14 into the upper part of the reaction tube 4, the downward bend at theend of the delivery pipe 14 causing a downward direction of flow D whichcan also be given a tangential component by a corresponding inclinationof the bent end of the pressure line 14.

The downwardly directed stream carries with it the air bubbles on whichthe particles to be removed, particularly protein, are taken up. Thefurther the bubbles pass downwards, the greater does the upwardlydirected rising force become, so that the bubbles begin to come to astandstill in the stream or to rise upwards.

At the lower end the reaction tube has a cross-sectional enlargement 15in the form of a funnel section, which is adjoined by an end section ofthe reaction tube 4 which receives an end filter 16. The end filter 16consists of a filter sponge, possibly interspersed and/or coated withactive carbon, which is surrounded by a cage of which the top face isprovided with a central inlet opening 17 of about two thirds of thediameter of the tube, which is surrounded by several riser holes 18 ofsmaller diameter. At the bottom the filter 16 is provided with a screen19 so that the purified aquarium water can leave there as shown by thearrow E.

The filter 16 serves, as already mentioned, to ensure that any airbubbles which may get below the funnel 15 are held back in the filtersponge at the downward outlet from the reaction tube 4 and are caused torise in the reaction tube, the form described above preventing theascent from the sponge of large air bubbles which in the separatingtube, in countercurrent to the freshly dispersed water introduced, wouldimpair the foam formation.

As likewise already mentioned, in the upper part of the reaction tube 4the dewatering of the air bubbles enriched with the substances to beremoved takes place with the formation of foam. To optimise collectionhere, the foam is carried over into the foam head 5, which is regularlyemptied and which in the exemplary embodiment shown is plugged on to thereaction tube 4 by means of a plug connection 21, so that it can beremoved whenever necessary. Through the double-walled form of the foamhead 5, which can be seen from the representation in FIG. 1, an annularspace 22 is formed into which the foam rising through the conicallyinwardly tapering foam tube 23, which is shorter than the outer wall ofthe foam head, collects. The conical contour of the foam tube 23 takesaccount in an excellent manner of the fact that through the progressivedewatering the foam decreases in volume towards the top, so that in theannular space 22 a particularly optimal foam consistency is thenobtained. By removing a lid 24 which is provided on top of the foam head5 and is provided with air escape holes 25, the annular space 22 isexposed for cleaning out.

A particular advantage for manipulation is that the individualcomponents of the foam flotation separator are connected together byplug and socket joints, so that they can be taken apart and put togetheras modules, which greatly facilitates maintenance and assembly. Thus theprefilter 3 can be separated from the pump 2 in just the same way asthis can be separated from the reaction tube 4 and the foam head 5 fromthe reaction tube.

INDUSTRIAL APPLICATION

The form and arrangement of the individual components leads to anextremely practical device.

I claim:
 1. A foam flotation separator for sea water aquaria,comprising:a dispersion pump (2) having an intake side and a deliveryside, said intake side draws in water to be treated containingpollutants and gas, said gas is air or ozone or a mixture thereof; areaction chamber (4) connected thereto on the delivery side, thereaction chamber having a lower outlet end having a purified wateroutlet and an upper end foam outlet for a foam containing saidpollutant; a foam collector (5) having an open bottom on the upper endof the reaction chamber (4), and a cross-sectional enlargement (15) atthe lower, outlet end of the reaction chamber (4) below the connectionof the pump delivery side to the reaction chamber said cross sectionalenlargement (15) at the lower end of the reaction chamber being ofsufficient magnitude that a downward flow rate of gas and water isreduced so that the air bubbles come to a standstill and rise.
 2. Thefoam flotation separator according to claim 1, further comprising anintake-side prefilter (3) for the water to be treated.
 3. The foamflotation separator according to claim 1, having a vertically disposedtube as reaction chamber (4).
 4. The foam flotation separator accordingto claim 3, wherein enlargement (15) at the lower, outlet end of thevertically disposed reaction tube (4) is funnel-shaped.
 5. The foamflotation separator according to claim 1, having a downwardly directedwater and gas dispersion inlet (D) in the reaction chamber (4).
 6. Thefoam flotation separator according to claim 1, having a filter (16) atthe outlet end of the reaction chamber (4).
 7. The foam flotationseparator according to claim 6, wherein the filter (16) consists of afilter basket surrounding a filter sponge.
 8. The foam flotationseparator according to claim 6, wherein the filter (16) is an activecarbon filter sponge.
 9. The foam flotation separator according to claim7, wherein the filter basket has an outlet end and an inlet end with ascreen (19) at its outlet end and the inlet end is provided with acentral inlet opening (17) surrounded by smaller diameter riser holes(18).
 10. The foam flotation separator according to claim 1, wherein theopen-bottom foam collector (5) is fitted releasably on to the reactiontube (4).
 11. The foam flotation separator according to claim 1, whereinthe foam collector (5) is provided with a lid (24).
 12. The foamflotation separator according to claim 11, wherein the lid (24) isprovided with air escape holes (25).
 13. The foam flotation separatoraccording to claim 1, wherein the foam collector (5) is double-walledhaving an inner wall (23) and an outer wall, with the walls connectedintegrally together at lower rims thereof.
 14. The foam flotationseparator according to claim 13, wherein the inner wall (23) is shorterin the axial direction than the outer wall.
 15. The foam flotationseparator according to claim 13, wherein the walls are coaxial.
 16. Thefoam flotation separator according to claim 13, wherein the inner wall(23) forming a foam tube tapers in a funnel shape from the lower rimtowards the interior of the foam collector (5).
 17. The foam flotationseparator according to claim 16, wherein the largest cross-section ofthe foam tube(23) corresponds to that of the upper end foam outlet ofthe reaction chamber (4).
 18. The foam flotation separator according toclaim 2, wherein the reaction chamber (4), the collector (5), and theprefilter (3) all have circular cross sections.
 19. The foam flotationseparator (1) according to claim 1, wherein the dispersion pump has animpeller with a wheel (6) carrying a plurality of needles (8).
 20. Thefoam flotation separator according to claim 19 wherein the impeller hasa plurality of needle disks secured non-rotatable in axial succession onan axle (7).
 21. The foam flotation separator of claim 20 wherein theneedles (8) project perpendicular to the impeller axle (7) in the formof a star.
 22. The foam flotation separator of claim 20 wherein eachneedle disk carries eight to twelve needles (8) in a plane.
 23. The foamflotation separator of claim 20 wherein the needle disks are mountedangularly offset on the axle (7).
 24. The foam flotation separator ofclaim 20 wherein the needle wheel (6) consists of up to ten needle disksdisposed offset one after the other.
 25. The foam flotation separator ofclaim 20 having a pump-type-dependent adapter on to which the needledisks can be pushed.